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Old 04-29-2009, 06:01 PM   #1
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Hi Folks

I don't know if this is the right place for this post but I am sure someone will move me if I am not. I was down at the harbour this weekend talking to one of the local sailing school's instructors about the boats for sale locally. He told me that the idea of a monolithic fibreglass hull is a relatively modern concept and that most boats before the early 80's tended to spray fiberglass over a wooden framework. As we wandered around the yard, he pointed out a few of the older boats as we have not launched for the season yet and most are still in dry-dock. He pointed out a few where you could definitely see where the frames were beginning to create creases in the hull.

My question is, I suppose, is this true? I imagine it would not have been spontaneous mass-migration, if true. Can we say that the previous way of shaping hulls is inferior? I ask simply because I want to know what I am looking at when I look at a boat's hull. And of course, if boats before a certain date may be undesireable, then I will keep that in mind as we discuss the hull. Although I still have a real soft spot for the look of wood...

Does anyone have an opinion on this?

Kevin
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Old 04-29-2009, 06:29 PM   #2
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Well Kevin,

My hull was laid-up in 1978 using a female tool and massive amounts of fiberglass. Plugs taken from below the waterline show hull thickness greater than 2 inches and freeboard at around 1/2 to 3/4" thick.

I guess there were boats laid-up using male tools in a type of cold molding...but I wasn't old enough at the time to witness this being done.

The general concensus that I believe is that 1975 thru 1982 or 83, hulls were built with excessive amounts of composite essentially reproducing the thickness of the wood hulls they were replacing. It wasn't till the 80's that computational methods for strength of materials enabled hull designers to optimize lay-ups based on composite theory.

If I were looking to buy a used boat, I think I would start looking at 1979 to 1982 and make sure that the layup was performed in a continuous process using a solid laminate...no core material. The continuous process assures interply bonding if performed correctly.

Here is a good article to read: http://www.yachtsurvey.com/core_materials.htm
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Old 04-29-2009, 08:47 PM   #3
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Thanks Trim! So much to learn...

What do you think of the ETAP boats, generally speaking? They are supposed to be unsinkable...
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Old 04-29-2009, 11:50 PM   #4
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It's funny that we all get slightly different stories on the history and "best" eras of fiberglass. The first fiberglass hulls were laid up in the late 1950's. Hulls made in the 1960's into the lat 1970's were very heavy and solid fiberglass reproducing the thickness of the wood hulls they were replacing. Sometime in the 1980's things started getting "thinned" out AND a variety of core materials other than fiberglass itself started showing up in use--from balsa wood to foam core. Boats built in the 1980's might be the most "iffy" in terms of good hull whereas the older ones are bullet proof and the later ones learned from the mistakes of the 1980's.

Don't know how much is correct, but that's what I've heard.
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Old 04-30-2009, 01:18 AM   #5
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I'm only speaking from experience...both my hulls were built in late 70s with extremely thick lay-ups.
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Old 04-30-2009, 06:00 PM   #6
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Quote:
Originally Posted by Trim50 View Post
I'm only speaking from experience...both my hulls were built in late 70s with extremely thick lay-ups.
I wish I could remember where I saw a good write-up on the evolution of fiberglass hulls. It may have been in Good Old Boat. The earliest fiberglass hulls were quite small in the late 1950's and early 1960's. The larger boats that most cruisers today would be interested in didn't come along until the late 1960's it seems.

What I remember is that we were looking at boats at the time of reading the info and I made a mental note to focus on seeking out fiberglass boats built in the late 1960's through late 1970's. Some other info was that early fiberglass hulls didn't have the same fire retardant chemicals mixed into the resin and that when mfr's started doing that, there were a few years of problem hulls (blistering in particular) until they'd worked out all the bugs. The years on that were US hulls started mixing in retardants in the mid-1970's but Taiwanese hulls (and similar) didn't start mixing in the same retardants until the early 1980's. Thus, that gave us another "reinforcing" reason to look at 70's era fiberglass boats.

All this knowledge went right out the window when we purchased a boat though...

I do know that early fiberglass hulls are truly built in such a way that they are incredibly strong. I'd think any cruiser would be happy to voyage in one.

Regards,

Brenda
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Old 04-30-2009, 09:55 PM   #7
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The shipyard that built NAUSIKAA was an old traditional wood-building yard which had developed into building GRP boats for the Royal Swedish Navy. As a result of this, when they broke into the "pleasure market", they continued to build boats to naval specifications. Thus, their boats were built like battleships!

With a solid laminate for the hull the only weak point is the deck which is of snadwhich construction.

Having experienced a mine detonation at close range in a GRP hull (minehunter), I am convinced of the strength of this material. I need no further proof.

Aye // Stephen
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Old 05-01-2009, 04:20 PM   #8
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Here is a good article to read: http://www.yachtsurvey.com/core_materials.htm
Thanks for the article Trim. I added it to my night-table reading and it was the most fun of that stack! It seems that the author is inferring, but does not discuss, that there are numerous boats that do not use a core of any material. Although I will accept as truth that balsa is better than foam, etc... I was hoping that there was some clear analysis that contrasted the utility of have having a monolithic fibreglass hull as opposed to one with a core. For example, ETAP (ETAP Web Site) boasts that it is unsinkable given its core of what appears to be polystyrene.

Does anyone have experience with ETAP boats? Do they wear faster than a boat that was simply fibreglass?

Kevin
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Old 05-01-2009, 08:54 PM   #9
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Here is a good article to read: http://www.yachtsurvey.com/core_materials.htm
Oh yes, and thanks for getting me addicted to Yachtsurvey.com. What a really great web-site!!!
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Old 05-02-2009, 01:35 AM   #10
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Originally Posted by KevinBarr View Post
Thanks for the article Trim. I added it to my night-table reading and it was the most fun of that stack! It seems that the author is inferring, but does not discuss, that there are numerous boats that do not use a core of any material. Although I will accept as truth that balsa is better than foam, etc... I was hoping that there was some clear analysis that contrasted the utility of have having a monolithic fibreglass hull as opposed to one with a core. For example, ETAP (ETAP Web Site) boasts that it is unsinkable given its core of what appears to be polystyrene.

Does anyone have experience with ETAP boats? Do they wear faster than a boat that was simply fibreglass?

Kevin
As I mentioned, we looked into this sort of thing while boat shopping but then after buying (a wooden) boat, I pretty much did a mind-dump of the info.

The article you refer to is very good in that he talks about the change going from the 1965 era all fiberglass hull to later iterations of balsa core and then other materials for core. All the shifting of use of different core materials seems to be mostly cost basis rather than performance based.

Intuitively, to me, it appears that an all-fiberglass and resin boat is going to have enhanced survivability over one sandwiched up with a core material. It seems the core materials only work well, structurally, in the hull when they are reinforced by the fiberglass and resin. Once the fiberglass resin layer has been compromised, the hull is at great risk--for example if you're grounded hard. Those core materials appear to have limited inherent structural utility. While balsa seems better than foam core, at least foam core doesn't degrade and turn into mush the way balsa can when boat owners add thru-hulls or other penetrations through the hull without proper blocking and sealing.

You are looking for "clear analysis" which may not exist--and if it does, if you're not a technical person, you may not really appreciate and derive a viewpoint from the nuances of the analysis anyway.

However, the material properties inclusive of strength of each material used in construction of the hull should be known by the designer/ manufacturer of the hull and it seems reasonable to request the information from a manufacturer. There may be a good handbook available to naval architects that you can look through as well. I personally am only familiar with the range of books which speak to wood boat design such books by Skene, Chapelle, and Steward. There are surely good books out there for designers of fiberglass or composite boats, I just am not familiar with them.

Best of luck to you in your search for additional information. Hopefully some other Cruiser Log readers can add to this discussion.

Fair winds
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Old 05-03-2009, 01:26 PM   #11
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Being new to boat ownership and having the chrysler C-22 finding me, its threads like this that I am learning the more I like it. It seems to be a type of Etap vessle. Made in 75 it is very thick fiberglass foam filled twin hull. There doesnt seem to be any deteriation(sp) where I can see a fair enough amount of it. the inner hull construction seems to give much strangth to the outer.

Said to be unsinkable so the name Titanic is out.

I have nice teak accents thru out it, but adding "just a little more" to give me a warm feel. Yes I think an all wood ship would be great.

I'm also happy I found this site.

Mario
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Old 05-04-2009, 06:44 PM   #12
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You are looking for "clear analysis" which may not exist--and if it does, if you're not a technical person, you may not really appreciate and derive a viewpoint from the nuances of the analysis anyway.
Thanks Red,

I am starting to think that like wine, different vintages and years produce variable results. And you are probably right in that there is likely no comprehensive compendium to evaluate different boats. So I think that I am going to do it. I am a researcher by trade, and this is of interest to me.

I am going to begin by compiling as comprehensive a list of manufacturers as possible. I am not sure how far back the data goes but I am going to establish the cut-off benchmark at 1965. This is an arbitrary number, but I think the majority of the available recorded data will be accessible long after this year. You never know, I might be able to find something where some of this is done already.

The real devil will be in the details: the methodology. I need to determine a set of indicators that I can evaluate against. I have some preliminary thoughts about this sort of things beyond the normal builder, year, model, plant location, etc… but maybe the community here has some ideas. Things that I am stumbling over is how to represent disparate hulls, such as how the core is laid out in the hull, thicker in some places, thinner in others. Is it bellow the water line? Thickness of various layers…

I would also like to include a "pros/cons" and background area. The background will give any information that I can dig up about the development of the boat, the company that designed/fabricated it and any particular organizations/clubs that support it. The pro/con section will discuss (possibly subjective) points about how it handles, sail plan and rigging, features as they apply to the cockpit and below decks. As most of the boats I will not have sailed, perhaps people can offer up their experiences on this count?

Any help that you folks can give would likely increase my knowledge by an order of magnitude greater than what I have already.

Cheers,

Kevin
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